Reclosable package having internal seal made of double-sided adhesive tape

ABSTRACT

Reclosable packages having a slider-actuated string zipper and a tamper-evident feature. In one aspect, the reclosable package comprises: a receptacle having a mouth and an interior volume; a string zipper installed in the mouth; a slider mounted to the string zipper; and a tamper-evident feature that blocks access to all or a portion of the interior volume. The tamper-evident feature is in the form of a strip of double-sided adhesive tape adhered to opposing walls of the receptacle to form a hermetic seal that partitions the interior volume of the receptacle. During manufacture of one embodiment, the adhesive tape with a release paper on one side is unwound from a reciprocating spool; the exposed side is pressed against a web of film; the release paper is removed; the web of film is folded; and then the folded-over portion of the web is pressed against the other side of the adhesive tape. A pair of zipper strips are also joined to the web in parallel with the adhesive tape.

RELATED PATENT APPLICATION

This application is a continuation-in-part of and claims priority from U.S. patent application Ser. No. 10/617,234 filed on Jul. 10, 2003 and entitled “Tamper-Evident Reclosable Bag Having Slider-Actuated String Zipper”.

BACKGROUND OF THE INVENTION

This invention generally relates to reclosable bags and other packages having profiled (e.g., extruded) plastic zippers and tamper-evident features. In particular, the invention relates to reclosable bags and other packages having a tamper-evident feature on the product side of the zipper.

In the use of plastic bags, pouches and other packages, particularly for containing foodstuffs, it is important that the bag be hermetically sealed and tamper evident until the purchaser acquires the bag and its contents, takes them home, and opens the bag or package for the first time. It is then commercially attractive and useful for the consumer that the bag or package be reclosable so that its contents may be protected. Such bags provide the consumer with the ability to readily store, in a closed, if not sealed, package any unused portion of the packaged product even after the package is initially opened. Flexible plastic zippers have proven to be excellent for reclosable bags, because they may be manufactured with high-speed equipment and are reliable for repeated reuse.

Many reclosable bags comprise a receptacle having a mouth with a slider-actuated zipper installed therein for opening and closing the bag. As the slider is moved in an opening direction, the slider causes the zipper sections it passes over to open. Conversely, as the slider is moved in a closing direction, the slider causes the zipper sections it passes over to close. Typically, a zipper for a reclosable bag includes a pair of interlockable profiled closure strips that are joined at opposite ends of the bag mouth. The profiles of interlockable plastic zipper parts can take on various configurations, e.g. interlocking rib and groove elements having so-called male and female profiles, interlocking alternating hook-shaped closure elements, etc. Reclosable bags having slider-operated zippers are generally more desirable to consumers than bags having zippers without sliders because the slider eliminates the need for the consumer to align the interlockable zipper profiles before causing those profiles to engage.

Various additions to reclosable bags have been made to provide tamper-evident seals or indicators that will reveal when the bag has been opened or otherwise tampered with prior to purchase by the consumer. It is known to provide a reclosable package construction that is designed to undergo some permanent change in the package appearance when the package is opened for the first time. For example, it is known to provide a reclosable package with a tamper-evident, non-reclosable peel seal that gives a positive indication of having been broken when a package is first opened. It is also known to cover the zipper (with or without slider) under a shroud or inside an enclosed header on the top of the bag. Another type of tamper-evident feature is the provision of a membrane on the product side of the zipper that partitions the interior volume in an airtight manner.

There is a continuing need for new designs for reclosable bags with tamper-evident features for hermetic packages that can be manufactured at low cost.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is directed to reclosable bags and other packages that have a profiled plastic zipper and a tamper-evident feature on the product side of the zipper. The tamper-evident feature is a strip of double-sided adhesive tape adhered to opposing walls of the package and extending from one side seal to the other, thereby hermetically sealing and partitioning the portion of the package interior volume containing a perishable product. The invention is further directed to methods of manufacturing such packages.

One aspect of the invention is a reclosable package comprising: a receptacle having a mouth and an interior volume; a string zipper installed in the mouth; a slider mounted to the string zipper; and a tamper-evident feature that blocks access to at least a portion of the interior volume, wherein the tamper-evident feature comprises double-sided adhesive tape located within the interior volume and adhered to the receptacle, the adhesive tape comprising a substrate having respective continuous layers of adhesive material on both sides thereof.

Another aspect of the invention is a reclosable package comprising: first and second panels joined together along first and second side edges to form first and second side seals and sealed or connected at a bottom to form a receptacle having a mouth and an interior volume; a zipper installed in the mouth; and a strip of material having low-tack adhesive on both sides, the low-tack adhesive on one side of the strip being adhered to the first panel and the low-tack adhesive on other side of the strip being adhered to the second panel from the first side seal to the second seal at an elevation below the zipper, wherein the adhesive tape blocks access to at least a portion of the interior volume.

A further aspect of the invention is a method of making reclosable packages, comprising the following steps: (a) placing one side of a length of a double-sided adhesive tape in contact with a length of a web of packaging film along a first line of adhesion generally parallel to mutually parallel first and second edges of the length of web, the first line of adhesion being closer to the first edge than to the second edge; (b) joining the back of a length of a first zipper strip to the length of web along a first line of joinder generally parallel to the first and second edges of the length of web and closer to the first edge than to the second edge; (c) joining the back of a length of a second zipper strip to the length of web along a second line of joinder generally parallel to the first and second edges of the length of web and closer to the second edge than to the first edge; (d) placing product on a first area of the length of web located on one side of a centerline of the length of web generally parallel to the first and second edges; (e) folding the length of web along the centerline so that a second area of the length of web located on the other side of the centerline overlies the product; (f) placing the other side of the length of double-sided adhesive tape in contact with the confronting portion of the folded-over length of web along a second line of adhesion; and (g) respectively joining first and second portions of the length of web on one side of the fold line to third and fourth portions of the length of web on the other side of the fold line along first and second transverse lines of joinder that are generally parallel to each other and generally perpendicular to the first and second edges, whereby a receptacle is formed having a sealed interior volume with the product therein, the sealed interior volume being bounded by the fold line, the first and second transverse lines of joinder, and the adhesive tape.

Yet another aspect of the invention is a method of making reclosable packages, comprising the following steps: (a) adhering first and second sides of a strip of double-sided adhesive tape to first and second portions, respectively, of web material along first and second lines of adhesion that are generally parallel to each other; (b) joining first and second zipper strips to third and fourth portions, respectively, of the web material along first and second lines of joinder that are generally parallel to the first and second lines of adhesion, a distance between the first line of joinder and the first line of adhesion being generally equal to a distance between the second line of joinder and the second line of adhesion; (c) manipulating the web material so that the first and second portions of the web material confront each other and the third and fourth portions of the web material confront each other; (d) joining fifth and sixth confronting portions of the web material along a first transverse line of joinder generally perpendicular to the first line of joinder; and (e) joining seventh and eighth confronting portions of the web material along a second transverse line of joinder generally parallel to the first transverse line of joinder.

Other aspects of the invention are disclosed and claimed below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing showing a reclosable package having a slider-operated string zipper with slider end stops and an internal hermetic seal in accordance with one embodiment of the invention.

FIG. 2 is a drawing showing a fragmentary sectional view of the upper portion of the package depicted in FIG. 1. The zipper, seal and packaging film are shown sectioned in a plane in front of the closing end of the slider.

FIG. 3 is a drawing depicting a portion of a machine that continuously applies string zipper material and double-sided adhesive tape to a web of packaging film in accordance with one embodiment of the invention.

FIG. 4 is a drawing showing the positional relationships of the string zipper, adhesive tape and packaging film after the operations depicted in FIG.3.

FIG. 5 is a drawing showing a later stage in the method of manufacture partly depicted in FIGS. 3 and 4.

FIG. 6 is a drawing showing a further stage in the method of manufacture depicted in FIGS. 3-5.

Reference will now be made to the drawings in which similar elements in different drawings bear the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION

A reclosable package comprising a receptacle 2 and a flexible plastic string zipper 4, operated by manipulation of a slider 10, is shown in FIG. 1. When the slider is moved in one direction along the string zipper, a portion of the string zipper inside the slider is opened; when the slider is moved in the opposite direction, a portion of the string zipper inside the slider is closed. The receptacle 2 comprises front and rear walls, which for the sake of illustration are presumed to be optically transparent. The front and rear walls in this embodiment are sealed together at parallel side edges and are integrally connected by a fold line at the bottom of the receptacle. In an alternative embodiment, the front and rear walls could be sealed together along the sides and the bottom. The side seals may be formed by cutting the packaging film with a hot knife, in which case the seal approximates a line of joinder. Alternatively, each side seal may be a band-shaped zone of joinder of finite width.

The receptacle 2 may be made from any suitable film material, including thermoplastic film materials such as low-density polyethylene, substantially linear copolymers of ethylene and a C3-C8 alpha-olefin, polypropylene, polyvinylidene chloride, mixtures of two or more of these polymers, or mixtures of one of these polymers with another thermoplastic polymer. The person skilled in the art will recognize that this list of suitable materials is not exhaustive. Although not intended in a limitative sense, it is noted that the thickness of the film is preferably 2 mils or less.

The string zipper 4 is disposed between the confronting top marginal portions of the front and rear walls, but has been represented as solid lines to reflect the fact that the front wall is optically transparent. Thus, during slider travel the side walls of the slider 4 pass over the top marginal portions of the front and rear walls of the receptacle, which are joined to opposing sides of the string zipper, as will be explained in more detail below.

The package shown in FIG. 1 further comprises slider end stops 5 and 5′ for preventing the slider from sliding off the end of the zipper when the slider reaches the zipper closed or fully opened position. Such end stops perform dual functions, serving as stops to prevent the slider from going off the end of the zipper and also holding the two zipper strips together to prevent the package from opening in response to stresses applied to the profiles through normal use of the package. In accordance with one embodiment of the invention, the end stops comprise stomped areas on the zipper parts themselves. The stomped end stops comprise sections of the zipper parts that have been fused together and flattened at the ends of the zipper. During deformation, thermoplastic zipper material flows upward such that the end stops are raised in height above the peak of the undeformed zipper on which the slider rides. Such stomping can be carried out using ultrasonic welding equipment. The horn and anvil of the ultrasonic welding apparatus are specifically designed so that the ultrasonic stomping operation create a vertical hump on the zipper to stop the slider. Sufficient heat penetrates into the mass of the zipper profile in the end stop areas to fuse the zipper parts together. The slider end stops 5 and 5′ limit slider travel to the profiled track formed by the section of undeformed string zipper therebetween.

In accordance with one embodiment of the invention, an internal hermetic seal 50 is disposed inside the receptacle at an elevation above the packaged product (not shown) and below the string zipper (see also FIG. 2). The hermetic seal 50 is depicted in FIG. 1 as a pair of mutually parallel solid lines, the lower of the two lines being designated by the numeral 50. As shown in FIG. 2, the hermetic seal 50 comprises a strip of double-sided adhesive tape, which in turn comprises a polymeric substrate 52 coated on both sides with a respective lengthwise continuous layer 54, 56 of low-tack adhesive material. The strip of adhesive tape 50 extends the full width of the package, with the ends of the tape being captured in the side seals of the receptacle. One side of the adhesive tape 50 is adhered to the front wall 2 a of the receptacle, while the other side of the adhesive tape 50 is adhered to the rear wall 2 b. The adhesive tape 50 hermetically seals and partitions the interior volume of the receptacle. The adhesive layers 54 and 56 provide respective adhesive bonds with the contacting receptacle walls of sufficiently low strength that the consumer is able to pull the wall and tape apart without difficulty when access to the interior volume of the receptacle is desired.

Reclosable packages within the scope of the present invention may be similar to the exemplary package shown in FIGS. 1 and 2 or may have structures that differ. In accordance with the various embodiments, however, a tamper-evident internal hermetic seal is provided on the product side of the zipper. This tamper-evident internal hermetic seal maintains the freshness of the perishable product inside the package and bars access to the contents of the package even after the zipper has been opened. If the seal is broken, this is evidence that the package may have been tampered with.

Still referring to FIG. 2, at its top end, the receptacle 2 has an openable mouth, on the inside of which is an extruded plastic string zipper 4. The string zipper 4 comprises a pair of interlockable zipper parts or closure strips 6 and 8. Although FIG. 2 shows a rib and groove arrangement, the profiles of the zipper halves may take any form. For example, the string zipper may comprise interlocking rib and groove elements (as shown in FIG. 2) or alternating hook-shaped closure elements. The preferred zipper material is polyethylene or polypropylene. The top margins of the front and rear walls 2 a and 2 b (see FIG. 2) are respectively sealed to the backs of the zipper strips 6 and 8, e.g., by a conventional conduction heat sealing technique. Optionally, the top edges of the front and rear walls 2 a, 2 b (i.e., which edges constitute the “lip” of the mouth of and 8 by a separate sealing operation. The method and apparatus for accomplishing lip sealing will be described in detail later.

For the sake of completeness, the string zipper and slider in accordance with one embodiment will be described in greater detail. However, it should be appreciated that the structure disclosed hereinafter is exemplary only, and that structures of the zipper and slider may be varied without affecting the structure and function of the tamper-evident internal hermetic seal disclosed herein. For example, the invention is not limited in its application to packages having slider-operated string zippers. Instead the slider-zipper assembly could be of the type wherein the zipper strips are attached to the receptacle by way of flanges or fins. Alternatively, the package could have a flanged or string zipper without a slider.

Referring again to FIG. 2, the zipper in this example is an extruded plastic structure comprising mutually interlockable profiles. Zipper strip or part 8 comprises a base 14 and two generally arrow-shaped rib-like male closure elements or members 20 and 28, while zipper strip or part 6 comprises two pairs of hook-shaped gripper jaws 16, 18 and 22, 24 connected by a sealing bridge 12. Jaws 16 and 18 receive and interlock with the male element 20, while jaws 22 and 24 receive and interlock with the male element 28. Alternatively, one zipper part could have one male profile and one female profile, while the other zipper part has one female profile and one male profile, or the respective zipper parts could each have more than two sets of male and female profiles.

The sealing bridge 12 and the base 14 are resiliently flexible self-supporting structures having a thickness greater than the thickness of the package film. The male closure elements are integrally formed with the base 14, while the female closure elements are integrally formed with the sealing bridge 12. The upper margins of the walls 2 a and 2 b of the package are joined to the backs of the sealing bridge 12 and the base 14 respectively, as seen in FIG. 2. In particular, it should be noted that there are no unattached tail portions at the film edges to interfere with slider insertion on or travel along the zipper.

The end face of the upper edge of the base 14, which carries the male closure elements 20 and 28, is inclined at about a 45° angle to facilitate loading of the slider onto the zipper from above without snagging on a comer of the upper edge. The topmost portion 46 of wall 2 b is sealed against this inclined end face. Similarly, the topmost portion 48 of wall 2 a is sealed against the curved back of the gripper jaw 16. The bottom edge of the base 14 cooperates with a retaining ledge on the slider to increase the slider-pull-off resistance. For the same purpose, a rib 26 is formed on zipper part 6, the rib 26 cooperating with a retaining ledge on the other side of the slider.

In the slider-zipper assembly shown in FIG. 2, the slider 10 for opening or closing the reclosable zipper is generally shaped so that the slider straddles the zipper profiles. The upper margins of the receptacle walls 2 a and 2 b, which are joined to the backs of the zipper parts 6 and 8, are disposed between the respective zipper parts and the respective side walls of the slider.

The slider 10 comprises a top wall 32, a pair of side walls 34 and 36 connected to opposing sides of the top wall 32, the top wall 32 and side walls 34, 36 forming a tunnel for passage of the string zipper therethrough. The ends of the slider are open to allow the zipper to pass through. The width of the tunnel is substantially constant along the section that is divided by the plow 44 and then narrows from a point proximal to the end of the plow to the closing window at one end face of the slider. The narrowing section of the tunnel is formed by substantially planar, inclined interior surfaces (not shown in FIG. 2), which converge toward the closing window of the slider. These inclined surfaces funnel or squeeze the zipper parts toward each other, causing the zipper profiles to interlock, as the slider is moved in the closing direction. The side walls 34 and 36 are formed with concave curved indentations (not shown) where the user may place the tips of an index finger and a thumb for gripping the slider. Alternatively, convexities (e.g., ribs) could be formed on the sides of the slider to facilitate grasping.

The slider 10 in this particular example also comprises a plow or divider 44 that depends downward from a central portion of the top wall 32 to an elevation below the lowermost portions of each side wall. The plow 44 is disposed between opposing sections of the zipper parts that pass through the tunnel. The tip of the plow 44 is truncated and has rounded edges and flattened comers at opposing ends for facilitating insertion of the plow between the zipper profiles without snagging during automated slider insertion. The plow 44 comprises a beam having a cross-sectional shape that is a rectangle with rounded comers. The axis of the beam is generally perpendicular to the top wall of the slider. As the slider is moved in the opening direction (i.e., with the closing end leading), the plow 44 pries the impinging sections of zipper parts 6 and 8 apart.

Although the slider in the disclosed embodiment has a plow, the string zipper, if suitably designed, could be actuated by a slider that has no plow or separating finger.

In the embodiment depicted in FIG. 3, the slider 10 further comprises a retaining projection or ledge 41 that projects inward from the side wall 34 and a retaining projection or ledge 43 that projects inward from the side wall 36. These ledges project toward each other, forming respective latches for latching the slider onto the zipper. The ledges 41, 43 have substantially coplanar, generally horizontal upper surfaces on which the bottom edges of the zipper profiles can sit, thereby effectively latching the slider under the bottom edges of the zipper parts to increase slider pull-off resistance. The ledges 41 and 43 further comprise respective inclined bottom surfaces that extend downward and outward from the respective inner edges of the generally horizontal surfaces. The inclined surfaces 40 and 42 are each substantially planar, with the respective planes of these inclined surfaces intersecting at a line inside the tunnel that is parallel to the longitudinal axis of the slider. The inclined surfaces 40 and 42 serve to guide the respective zipper parts 6 and 8 into the slider tunnel during insertion of the slider onto an open section of the zipper.

The slider may be made in multiple parts and welded together or the parts may be constructed to be snapped together. The slider may also be of one-piece construction. The slider can be made using any desired method, such as injection molding. The slider can be molded from any suitable plastic, such as nylon, polypropylene, polystyrene, acetal, polyketone, polybutylene terephthalate, high-density polyethylene, polycarbonate, or ABS.

Improved slider designs are disclosed in U.S. patent application Ser. No. 10/412,438, entitled “Molded Sliders for Actuating Zippers of Reclosable Packages”. In one such design, each retaining ledge on the interior surface of the slider side walls is replaced by a pair of retaining teeth spaced apart at opposite ends of the slider.

FIGS. 3-6 show various stages in the manufacture of the reclosable package depicted in FIGS. 1 and 2. An automated system (partly shown in FIG. 3) is used to continuously apply a double-sided adhesive tape 50 and string zipper material 4 to one side of a web 2 of packaging film (monolayer or lamination). The web 2 is drawn from a supply roll 102. The drawn film passes around a guide roller 112 and is advanced to a nip formed by a pair of press rolls 114 and 116. The web 2 is advanced by pinch rollers (not shown) that pull the web through the machine. In the example shown in FIG. 3, the web 2 is advanced intermittently through the machine. At the same time, adhesive tape 50, with a continuous strip of release paper 51 adhered to one side of the tape, is drawn from a supply reel 104 and also passed through the nip formed by press rolls 114 and. 116 with the release paper facing away from the web 2. In the nip, the exposed side of the adhesive tape 50 is pressed against and adhered to the top surface of the web 2.

FIG. 4 shows the web 2 at a position downstream from the press rolls, namely, after the string zipper material 4 has also been joined to the web along the marginal portion between adhesive tape 50 and edge 64. The dashed line F in FIG. 4 represents where the web will later be folded, as explained in more detail below.

Returning to FIG. 3, downstream of the press rolls 114, 116, the web advances with the adhesive tape adhered thereto. The release paper 51 is still adhered to the other side of the adhesive tape 50. As the web, tape and release paper advance, the edge of a stationary separator blade 118 pries the release paper 51 and the adhesive tape 50 apart. The blade 118 redirects the separated release paper 51 away from the web and toward a take-out suction box 106, which sucks the discarded release paper into a bin for disposal or recycling. Removal of the release paper 51 exposes the layer of adhesive on the side of the adhesive tape opposite to the web of packaging film.

FIG. 3 shows that the string zipper material 4 is joined to the web 2 of packaging film after the release paper 51 has been removed. However, the order in which these operations are performed could be reversed. The string zipper material 4, comprising interlocked flangeless zipper strips, is drawn from a supply spool 108 and advanced intermittently. The supply spool 108 reciprocates from side to side along its axis of rotation to maintain the string zipper material in the same lateral position corresponding to the location of an ultrasonic welding assembly 110. If desired, an optical (or other) sensor (not shown) can be employed to detect an edge of the zipper material before the latter approaches the ultrasonic welding assembly and the lateral position of the supply spool 108 can be controlled by a programmed logic controller (not shown) as a function of feedback from the optical sensor, for example, via a servo motor (not shown) that can be activated to move the supply spool 108 in either lateral direction.

The ultrasonic welding assembly 110 comprises an ultrasonic horn 96 and an anvil 98. The string zipper material 4 is intermittently advanced through the gap separating the horn and the anvil. During each dwell time, the horn is displaced toward the anvil, e.g., by means of an air-actuated cylinder (not shown), and activated to transmit ultrasonic wave energy into a respective portion of the thermoplastic zipper material being pressed between the horn and anvil. During this operation, the thermoplastic zipper material is softened and deformed into a slider end stop structure. This slider end stop structure will be bisected later when the packaging film and string zipper are cut in the cross direction using a hot knife that both severs and seals the film.

Alternatively, the string zipper material could be ultrasonically stomped to form slider end stop structures at a different site and wound on the supply spool, which is then transported to and mounted on the bag making machine. The pre-stomped string zipper material can then be unwound from the spool and fed to the zipper sealing station.

In either case, the drawn string zipper material is passed through a zipper guide 120 that is laterally situated between an edge of web 2 and the adhesive tape 50 adhered to the web. In its simplest form, the zipper guide may be a tube that maintains the zipper in the proper position and orientation relative to the web 2, which in this case is parallel to the edge of the web and overlying the marginal web portion disposed between that edge and the adhesive tape, as seen in FIG. 4. At a first zipper sealing station 122, this marginal portion of the film web 2 is joined to the back of one zipper strip of the string zipper material 4 by a pair of mutually opposing reciprocating sealing bars 124 and 126. Sealing bar 124 is unheated, while sealing bar 126 is heated. When both sealing bars are extended, the web 2 and the string zipper material 4 are pressed together and the back of one zipper strip is conduction heat sealed to the web by the heat from the heated sealing bar 126. The heated sealing bar 126 forms a band-shaped zone of joinder between the film and a central portion of the back of the adjacent zipper strip. This zone of joinder then becomes the permanent seal joining a portion of wall 2 b to the back of the zipper strip 8, as seen in FIG. 2.

Downstream from the first zipper sealing station 122, a mass of product 70 is placed on the web 2 on the same side of the fold line F as the adhesive tape 50 and the string zipper material 4, as seen in FIG. 5. The other side of the web 2 is folded along line F, as indicated by the curved arrow in FIG. 5. The folding operation can be performed by advancing the web over and past a conventional stationary folding board or plow (not shown). As seen in FIG. 6, the folded-over portion of the web 2 will overlie the product 70, the adhesive tape 50 and the string zipper material 4, with edge 62 of the web overlying and generally parallel to the edge 64. The operations for attaching the other side of the adhesive tape and the other zipper strip to the folded-over portion of the web are the mirror image of the similar operations previously described, namely, the folded-over portion of the web is pressed against the side of the adhesive tape having exposed adhesive by another pair of press rolls and is heat sealed to the back of the other zipper strip of the string zipper by a pair of sealing bars, the upper bar being heated and the lower bar being unheated. Again, the heated sealing bar forms a band-shaped zone of joinder between the film and a central portion of the back of the adjacent zipper strip. This zone of joinder then becomes the permanent seal joining a portion of wall 2 a to the back of the zipper strip 6, as seen in FIG. 2.

As seen in FIG. 6, excess film that extends beyond the string zipper 4 is trimmed by a pair of knives 72 and 74. Each knife trims a respective marginal portion of the film that extends beyond the tops of the zipper strips. The tips of the knife blades must be positioned so as to not cut the zipper, even during zipper wandering to and fro. The trimmed portion of the film is taken away by means not shown in FIG. 6. However, the aforementioned tail portions 46 and 48 (shown attached to the zipper in FIG. 2) are not yet attached immediately subsequent to the trimming operation. The presence of such unattached film tails could interfere with slider insertion during manufacture as well as with slider operation during use of the reclosable package by a consumer. Therefore an additional step is performed of sealing the tails to the respective zipper strips. The tails can be sealed by a lip sealer (not shown) of the type disclosed in U.S. patent application Ser. No. 10/655,991 entitled “Method and Apparatus for Making Reclosable Bags Having Slider-Actuated String Zippers”.

In the next stage of manufacture, a respective slider 10 is inserted onto the string zipper 4 by a slider insertion device 80, generally depicted in FIG. 6, after each advancement of the film. The slider insertion device 80 comprises a pusher 82 that pushes a slider 10 with a separating finger onto a partly open section of the string zipper. [Apparatus for maintaining a string zipper in a partly open state at a slider insertion zone is disclosed in U.S. patent application Ser. No. 10/436,433 entitled “Method and Apparatus for Inserting Sliders During Automated Manufacture of Reclosable Bags”.] The pusher displacement is driven by an air cylinder 86. The pusher 82 is fixed to a distal end of a rod 84 of a piston slidable inside the cylinder 86. The pusher 82 is alternately extended and retracted by actuation of the air cylinder 86, which has two separate ports (not shown) for intake of compressed air from separately controlled air lines. A succession of sliders 10 are fed periodically along a track (not shown) by a conventional pneumatic slider feeding system (not shown). When the pusher 82 is retracted, the next slider is fed automatically to a pre-insertion position directly in front of the pusher, as depicted in FIG. 6. The final position of the fully inserted slider on the string zipper can be seen in FIG. 2.

After each slider insertion, the web/zipper/slider/adhesive tape assembly is advanced one package width. A cross sealing station (not shown in the drawings) is located downstream from the slider insertion device. After each package-width advance, the web is cross sealed by a pair of opposing reciprocating vertical heated sealing bars at the cross sealing station. These vertical sealing bars form a cross seal that extends from the fold in the web to the edges of the web. Slider insertion and cross sealing occur during the same dwell time at different locations along the tensioned web. A cutting station is located downstream of the cross sealing station. The cutting station comprises a knife for cutting the web and zipper along a vertical line that generally bisects each cross seal, thereby severing an individual package from the web/zipper/slider/adhesive tape assembly. Alternatively, cross sealing and cutting can be performed concurrently using a hot knife. The end result is a package having product hermetically sealed by the adhesive tape, which partitions the interior volume of the package at an elevation just below the slider-operated string zipper.

In the example shown in FIG. 3, the web 2 was advanced intermittently through the bag making machine. However, a person skilled in the art will recognize that, upstream of the zipper sealing station, the web could be advanced continuously provided that a dancer assembly is installed between the adhesive tape application station and the zipper sealing station to transition the web advancement from continuous to intermittent. Optionally, if the string zipper has been pre-stomped with slider end stops and is being unwound from a spool in a pre-stomped state, then the web could be advanced continuously over a folding board (not shown) and the string zipper material 4 could be sealed to the advancing web by respective sets of drag sealers upstream and downstream with respect to the folding board. In the latter case, the web could be advanced continuously to a dancer assembly installed immediately upstream of the slider insertion device. The folded web and attached string zipper material would then proceed intermittently, one package width per advance, to the slider insertion device.

Alternatively, the zipper and adhesive tape could be continuously attached to the web so that the dancer assembly could be placed after the zipper sealing station and that both zipper bases could be sealed at the same time to a folded web by drag sealers on either side of the zipper.

While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for members thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

As used in the claims, the verb “joined” means fused, bonded, sealed, adhered, etc., whether by application of heat and/or pressure, application of ultrasonic energy, application of a layer of adhesive material or bonding agent, interposition of an adhesive or bonding strip, etc. As used in the claims, the term “string zipper” means a zipper comprising two interlockable closure strips that have substantially no flange portions. In the method claims, various lines of joinder are identified by the adjectives “first”, “second”, and so forth, which identifiers should not be construed to imply any order in which the various recited steps of the claimed method are performed. Furthermore, as used in the claims, the term “line of joinder” should be construed broadly to encompass a line of joinder as well as a band- or strip-shaped zone of joinder having a finite width. 

1. A reclosable package comprising: a receptacle having a mouth and an interior volume; a string zipper installed in said mouth; a slider mounted to said string zipper; and a tamper-evident feature that blocks access to at least a portion of said interior volume, wherein said tamper-evident feature comprises double-sided adhesive tape located within said interior volume and adhered to said receptacle, said adhesive tape comprising a substrate having respective continuous layers of adhesive material on both sides thereof.
 2. The package as recited in claim 1, wherein said substrate comprises a polymeric film coated on both sides with adhesive material.
 3. The package as recited in claim 2, wherein said adhesive material is a low-tack pressure-sensitive adhesive.
 4. The package as recited in claim 1, wherein said adhesive tape extends the full width of said receptacle and generally parallel to said string zipper.
 5. The package as recited in claim 4, wherein said receptacle comprises first and second panels, and said adhesive tape is adhered to said first and second panels.
 6. The package as recited in claim 5, wherein said first and second panels have their respective opposing side edges sealed together to form first and second side seals on respective sides of said receptacle, and said adhesive tape has first and second ends that are respectively captured between said side edges of said first and second panels at said first and second side seals respectively.
 7. A reclosable package comprising: first and second panels joined together along first and second side edges to form first and second side seals and sealed or connected at a bottom to form a receptacle having a mouth and an interior volume; a zipper installed in said mouth; and a strip of material having low-tack adhesive on both sides, the low-tack adhesive on one side of said strip being adhered to said first panel and the low-tack adhesive on other side of said strip being adhered to said second panel from said first side seal to said second seal at an elevation below said zipper, wherein said adhesive tape blocks access to at least a portion of said interior volume.
 8. The package as recited in claim 7, wherein said zipper comprises a first flangeless zipper strip sealed to said first panel and a second zipper strip sealed to said second panel.
 9. The package as recited in claim 8, further comprising a slider mounted to said zipper with respective marginal portions of said first and second panels being disposed between the side walls of said slider and the backs of said first and second zipper strips respectively.
 10. The package as recited in claim 7, wherein said strip is made of polymeric material.
 11. The package as recited in claim 7, wherein said adhesive tape has first and second ends that are respectively captured between said side edges of said first and second panels at said first and second side seals respectively.
 12. A method of making reclosable packages, comprising the following steps: (a) placing one side of a length of a double-sided adhesive tape in contact with a length of a web of packaging film along a first line of adhesion generally parallel to mutually parallel first and second edges of the length of web, said first line of adhesion being closer to the first edge than to the second edge; (b) joining the back of a length of a first zipper strip to the length of web along a first line of joinder generally parallel to the first and second edges of the length of web and closer to the first edge than to the second edge; (c) joining the back of a length of a second zipper strip to the length of web along a second line of joinder generally parallel to the first and second edges of the length of web and closer to the second edge than to the first edge; (d) placing product on a first area of the length of web located on one side of a centerline of the length of web generally parallel to the first and second edges; (e) folding the length of web along the centerline so that a second area of the length of web located on the other side of the centerline overlies the product; (f) placing the other side of the length of double-sided adhesive tape in contact with the confronting portion of the folded-over length of web along a second line of adhesion; and (g) respectively joining first and second portions of the length of web on one side of said fold line to third and fourth portions of the length of web on the other side of said fold line along first and second transverse lines of joinder that are generally parallel to each other and generally perpendicular to the first and second edges, whereby a receptacle is formed having a sealed interior volume with said product therein, said sealed interior volume being bounded by said fold line, said first and second transverse lines of joinder, and said adhesive tape.
 13. The method as recited in claim 12, wherein step (b) is performed prior to step (e) and step (c) is performed subsequent to step (e).
 14. The method as recited in claim 12, wherein steps (b) and (c) are performed prior to step (e).
 15. The method as recited in claim 14, further comprising the step of interlocking the closure profiles of said lengths of said first and second zipper strips.
 16. The method as recited in claim 15, wherein said interlocking step is performed prior to steps (b) and (c).
 17. The method as recited in claim 15, wherein said interlocking step is performed subsequent to steps (b), (c) and (e).
 18. The method as recited in claim 15, further comprising the step of mounting a slider to said lengths of said first and second zipper strips.
 19. The method as recited in claim 12, further comprising the step of removing a length of a strip of release material that is adhered to one side of the length of adhesive tape.
 20. The method as recited in claim 12, wherein step (a) comprises the step of pressing the adhesive tape against the web.
 21. The method as recited in claim 12, further comprising the steps of cutting said lengths of web and first and second zipper strips along said first and second transverse lines of joinder to form an individual package.
 22. A method of making reclosable packages, comprising the following steps: (a) adhering first and second sides of a strip of double-sided adhesive tape to first and second portions, respectively, of web material along first and second lines of adhesion that are generally parallel to each other; (b) joining first and second zipper strips to third and fourth portions, respectively, of said web material along first and second lines of joinder that are generally parallel to said first and second lines of adhesion, a distance between said first line of joinder and said first line of adhesion being generally equal to a distance between said second line of joinder and said second line of adhesion; (c) manipulating said web material so that said first and second portions of said web material confront each other and said third and fourth portions of said web material confront each other; (d) joining fifth and sixth confronting portions of said web material along a first transverse line of joinder generally perpendicular to said first line of joinder; and (e) joining seventh and eighth confronting portions of said web material along a second transverse line of joinder generally parallel to said first transverse line of joinder.
 23. The method as recited in claim 22, wherein product is placed on a portion of said web material prior to step (c).
 24. The method as recited in claim 22, wherein said web material comprises a length of a web having first and second mutually parallel edges, and said manipulating step comprises folding said length of web along a centerline halfway between said first and second edges.
 25. The method as recited in claim 22, wherein said first side of said strip of double-sided adhesive tape is adhered to said first portion of said web material before step (c) is performed, and said second side of said strip of double-sided adhesive tape is adhered to said second portion of said web material after step (c) is performed.
 26. The method as recited in claim 22, wherein said first zipper strip is joined to said third portion of said web material before step (c) is performed, and said second zipper strip is joined to said fourth portion of said web material after step (c) is performed.
 27. The method as recited in claim 22, further comprising the step of interlocking the closure profiles of said first and second zipper strips.
 28. The method as recited in claim 27, further comprising the step of mounting a slider to said interlocked first and second zipper strips.
 29. The method as recited in claim 22, further comprising the step of removing a strip of release material that is adhered to one side of said adhesive tape.
 30. The method as recited in claim 22, further comprising the steps of cutting said web material and first and second zipper strips along said first and second transverse lines of joinder to form an individual package.
 31. The method as recited in claim 22, wherein said web material comprises first and second webs, said first side of said adhesive tape being adhered to said first web, said second side of said adhesive tape being adhered to said second web, said first zipper strip being joined to said first web, and said second zipper strip being joined to said second web, and wherein said manipulating step comprises positioning said first and second webs in overlapping relationship, further comprising the step of joining confronting portions of said first and second webs along a line of joinder generally parallel to said first line of joinder. 